Inhalation is a way which is getting more and more important for the administration of pharmaceuticals. To this end, apart from the use of new locally acting pharmaceuticals for the therapy of lung diseases, new therapeutic strategies are developed making use of the lung as a site for systematically acting substances.
Regarding the application of drugs via inhalation, the demands on the quality of the inhalation process are increasing. The pharmaceutical dosage prescribed by the medical practitioner must be applied as exactly and reproducible as possible, wherein the administered dosage and its reproducibility depend basically on the breathing processes.
In everyday life in hospitals, the breathing maneuvers or processes by a patient cannot be influenced very much and evades medical control so that an exact guideline for respiratory volume and breath flow upon inhalation of therapeutic aerosols is desirable. This would lead to a significant improvement in the inhalation therapy and its reproducibility.
The administration of pharmaceuticals in the form of aerosol to the lung by inhalation is essentially influenced by four factors: (i) the particle size and particle properties of the aerosol; (ii) the volume inhaled by the patient in one breath; (iii) the patient's respiratory flow; and (iv) the patient's morphometry and respiratory system. Although aerosols in suitable particle size ranges are produced by the conventional systems, the parameters “respiratory volume” and “respiratory flow” (rate of breathing) are taken into account either insufficiently or not at all in known systems. This leads to an uncontrolled inhalation of the aerosol, which in turn has the result that the aerosol particles reach the lung in insufficient amounts or do not reach the areas (e.g., the alveolar area) within the lung to be treated.
WO 98/52633 discloses a device for administering a pharmaceutical via the lung comprising a mouthpiece for inhalation to which an adjustable atomizer is assigned, and a compressed air control valve through which a predefinable volume flow of compressed air can be delivered for a predefinable period to the atomizer containing the liquid medicine. Such a compressed air control valve is indispensable in the known inhalation device since high pressures are necessary to atomize the drug.